PORTSMOUTH, N.H. — Two men have been charged with selling a form of synthetic marijuana in New Hampshire and Maine.

Kyle Hurley and Robert Costello are being held without bail following their arrest March 28 after a three-month investigation. It wasn’t immediately known if they had lawyers.

The Portsmouth Herald reports the investigation took undercover agents to Portsmouth, Hampton, Seabrook and Kittery, Maine. It started with the purchase of synthetic marijuana from a Londonderry store on Dec. 31.

Costello allegedly told police he worked with someone who had a barn in Epping, where that person mixes the marijuana in cement mixers and then spreads it on plastic sheets. The product is then sprayed with synthetics.